Abstract: An integrated circuit having a plurality of interdependent differential pairs of CMOS transistors emulates the functional characteristics of a biological neuron. The gate voltage of a first one of each pair of transistors is settable to a threshold value corresponding to an activation threshold of an ion channel in the biological neuron and the gate of a second one of each pair of transistors is representative of an incoming membrane potential, ligand concentration or ion concentration of the biological neuron. Each differential pair of CMOS transistors provides a sigmoidal output representative of an ionic conductance across a neuron membrane when the gate voltage of the second transistor exceeds the threshold value set by the gate voltage of the first transistor.